Nu-alkyl-nu&#39;-(p-hydroxyphenyl) ureas as antioxidants for petroleum hydrocarbon fuels



Patented July 6, 1954 UNITED STATES PATENT OFFICE N -ALKYL-N'- (p HYDROXYPHENYL) URE'AS AS ANTIOXIDANTS FOR PETROLEUM HY- DRQCARBON FUELS Eugene F. Hill, Detroit, and David 0. De Pree,

Royal ak,'Micl1., assignors to Ethyl Corporation, New York, N. Y., a corporation of Dela- Ware N0 Drawing. Original application December 9,

1950, Serial No. 200,112 Divided and this application July 26, 1952, Serial No. 301,167

8 Claims.

. class of substances which are powerful gasoline antioxidants. So far as we are aware it has not previously been known that the mere addition of an alkyl group to an otherwise inactive compound would produce thereby a material which would prevent deterioration of petroleum hydrocarbons by the action of oxygen.

Thereforeit is an object of our invention to provide a new class of antioxidant materials useful in protecting petroleum hydrocarbons from deterioration in'the presence of oxygen or air. In particular it is an object of our invention toprovide a new class of materials which prevent the deterioration of motor fuels by oxygen.

In accordance with our invention we provide new .ureas which contain the structure wherein R is an alkyl group. By the term alkyl we mean saturated, straight, or branched chain or cyclic aliphatic hydrocarbon radicals.

Examples of such alkyl radicals include methyl,

ethyl, propyl, n-octadecyl, isopropyl, isobutyl, sec-butyl, 2-rnethylhexyl, cyclohexyl, methylcyclohexyl, B-cyclohexylethyl, etc.

The free amine from which our compounds may be considered as being derived, in addition to being inactive as an antioxidant, possesses a low degree of solubility in petroleum hydrocarbons. However, by substituting an alkyl group on the free amine nitrogen, in accordance with our invention, we not only increase the solubility in petroleum hydrocarbons but obtain the unexpected result that we thereby create an antioxidant material which is as potent as many commercial antioxidants and more potent than several.

As examples of the alkyl groups which can be substituted in accordance with our invention We include methyl, ethyl, n-propyl, isopropyl, and the various isomeric butyl, amyl, and octyl radicals. However, we find that We can increase the alkyl chain beyond the limits enumerated above without impairing the antioxidant qualities of our invention. For example, when the alkyl group is as high as dodecyl or even octadecyl We still obtain extremely active antioxidant materials. As further examples of the alkyl groups which we can substitute in the compounds of our invention we include cyclohexyl and hydrocarbon substituted cyclohexyl radicals, as well as aralkyl radicals such as, for example, benzyl and hydrocarbon substituted benzyl radicals.

In general the compounds of our invention are prepared readily and in good yield by treating alkylisocyanates with p-aminophenol. In the examples which follow We illustrate the preparation of specific examples of the novel compounds of. our invention, and in these examples all parts and percentages are by weight.

EXAMPLE I N -n-propyl-N (p-hydroxyphenyl) wear-To a vessel provided with an agitator, means for returning reflux to the reaction vessel, means for introducing liquid reactants; and means for supplying heat was added 100 parts of p-aminophenol and 300 parts of toluene. This mixture was heated to a temperature of 50 C. and parts of n-propylisocyanate was added over a period of one and one-quarter hours. At the end or the addition the mixture was heated for an additional period of 30 minutes. The reac-' tion mixture containing the product as a sus--- pended solid'was filtered and the N-(n-propyl) N-(p-hydroxyphenyl)urea, 130 parts, was re-.

covered in 6''! per cent yield based upon the p-aminophenol employed.

EXAMPLE II EXAMPLE In N (mired-amyl) N (p-hydrowyphenyburea.In accordance with the procedure of Example I, parts of p-aminophenol in 300 parts of toluene was treated with 101 parts of (mixed) amylisocyanates to produce N-(mixed-amyl) N'-(p-hydroxyphenyl) urea. This product had a melting point of 180 C. with decomposition.

EXANIPLE IV N -n-octyl-N (p-hydroxyp-henyl) urea.In accordance with the procedure of Example I, 100 parts of p-aminophenol in 300 parts of toluene was treated with 142 parts'of n-octylisocyanate. This product, N-n-octyl-N-(p-hydroxyphenyl)- urea, had a melting point of 131 C.

EXAIVIPLE V N -n-butyZ-N (p-hydroxyphenyl) urea.In accordance with the procedure of Example I, 100 parts of p-aminophenol in 300 parts of toluene was treated with 99 parts of n-butylisocyanate to produce N-n-butyl-N'-(p-hydroxyphenyl)- urea having a melting point of 158 C.

EXAMPLE VI N n dodecyl N (p hydroozyphenyl) urea..In accordance with the procedure of Example I, 100 parts of p-aminophenol in 300 parts of toluene was treated with 188 parts of dodecylisocyanate to produce N-n-dodecyl-N-(p-hydroxyphenyDurea having a melting point of 142 C.

The compounds of our invention are excellent antioxidants and we have illustrated this property in the table, wherein we have listed the results obtained by determining the oxidation stability of gasoline according to the Induction Period Method, ASTM designation: D525-46, as fully described in Part III-A, AS'I'M Standards for 1946. We have employed gasoline in this determination since it is representative of an important class of industrial products which are susceptible to deterioration, and for which it is important to provide stabilizing materials. The column headed IPI lists the Induction Period Increase, in minutes, over that of the gasoline in the absence of the antioxidants of our invention. That is, under the conditions of test, each gasoline exhibits a period, typical of the gasoline, wherein oxygen is not absorbed. In the resence of our inhibitors this period is increased by the amount listed under IPI. The lack of eifectiveness of N-(p-hydroxyphenyl) urea is shown by compound No. 8 in the table.

N-noctyl-N (p-hydroxyphcnyl) urea N-n-dodecyl-N- (p-hydroxyphenyDurea N-n-propy1N- (p-hydroxyphcnyDurea N-cyclohexyl-N" (p-hydroxyphenyl)urea N -nbutyl-N '(p-hydroxyphenyl) urea N-n-octadecyl-N (p-hydroxyphenyl) urea N- (p-hydroxyph enyhurea We have disclosed a number of embodiments of our invention and illustrated several methods whereby these materials can be prepared. However, our invention is not intended to be limited to the specific examples herein or to the means 4 described herein for obtaining our novel compounds.

We claim:

1. A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount sufii'cient to prevent such deterioration. an antioxidant material consisting of an N'-(p-hydroxyphenyl) urea substituted on the N-nitrogen atom with a member selected from a group consisting of acyclic and cyclic saturated paraffin radicals containing up to about 18 carbon atoms.

2. A new petroleum hyd'rocarbonfuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount sufficient to prevent such deterioration, an antioxidant material consisting of an N-(p-hydroxyphenyl) -urea substituted on the N-nitrogen atom with an acyclic saturated paraffin radical containing up to about 18 carbon atoms.

3. A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount suflicient to prevent such deterioration, an antioxidant material consisting of an N-(p-hydroxyphenyl) urea substituted on the N -nitrogen atom with a cyclic saturated paraiiin radical containing up to about 18 carbon atoms.

4. A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount sufficient to prevent such deterioration, an antioxidant material consisting of N-cyclohexyl-N (p-hydroxyphenyl) -urea.

5. A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount suficient to prevent such deterioration, an antioxidant material consisting of N-n-propyl-N -(p-hydroxypheny1) -urea.

6. A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount sufiicient to prevent such deterioration, an antioxidant material consisting of N-(mixed-amyl) -N-(p-hydroxyphenyl) -urea.

7, A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount sufficient to prevent such deterioration, an antioxidant material consisting of N-n-octyl-N-(p-hydroxyphenyl) -urea.

8. A new petroleum hydrocarbon fuel composition stable to oxidation consisting essentially of gasoline, normally susceptible to deterioration by oxygen and, in amount sufiicient to prevent such deterioration, an antioxidant material consisting of N-n-dodecyl-N' (p-hydroxyphenyl) -urea.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,266,601 Howland Dec. 16, 1941 2,477,872 I-Iaury Aug. 2, 1949 

1. A NEW PETROLEUM HYDROCARBON FUEL COMPOSITION STABLE TO OXIDATION CONSISTING ESSENTIALLY OF GASOLINE, NORMALLY SUSCEPTIBLE TO DETERIORATION BY OXYGEN AND, IN AMOUNT SUFFICIENT TO PREVENT SUCH DETERIORATION, AN ANTIOXIDANT MATERIAL CONSISTING OF AN N''-(P-HYDROXYPHENYL) UREA SUBSTITUTED ON THE N-NITROGEN ATOM WITH A MEMBER SELECTED FROM A GROUP CONSISTING OF ACYCLIC AND CYCLIC SATURATED PARAFFIN RADICALS CONTAINING UP TO ABOUT 18 CARBON ATOMS. 